An optical mouse has advantages over a computer mouse that relies on the physical rolling of a ball. A variety of optical mouses are widely available. However, the optical mouses in current commercial use have a number of disadvantages.
One disadvantage is that the thickness or height from the work surface is typically larger when compared to roller-type computer mouses due to constraints imposed by the optical projection and imaging systems included therein. This increase in thickness can be uncomfortable and lead to fatigue for the user. Another disadvantage is that the optical design is unduly complex, typically requiring changes of direction on two or more reflecting surfaces. This leads to additional component and assembly costs.